Cocoa Recall

Flavonoids, a group of chemicals commonly found in plants, are often credited as having “superfood” powers. One of them, epicatechin (epi)—abundant in chocolate, green tea, and red wine—allegedly reduces the risk of heart disease, diabetes, and cancer, among other virtues. It is also thought to improve memory. But is that so? The answer, for the memory benefit, is yes, at least if you are a snail.

Neuroscientist Kenneth D. Lukowiak of the University of Calgary, Canada, and two colleagues tested the power of epi as a memory enhancer in the pond snail Lymnaea stagnalis. Pond snails breathe through their skin when in waters rich in oxygen, but if oxygen becomes scarce, the mollusks go to the surface and breath through an orifice—the pneumostome—connected to a simple lung. By gently poking the pneumostome with a stick when a snail tries to open it, researchers can condition snails to come up for air less frequently. And that’s what the team did.

They trained snails with the stick in plain pond water and in epi-infused water and compared the duration of their memory. After a half-hour session, snails in plain water learned to attempt fewer breaths—and remembered their lessons for about three hours. Snails exposed to epi, on the other hand, kept up their modified behavior a full day later. And snails trained in epi-rich water for two half-hour sessions continued to surface less often for air three days on. Snails trained in epi also had stronger memories than snails trained in regular water—that is, it was harder to train them to ignore what they had learned.

Epi still improved snail memory after the researchers blocked the animals’ serotonin receptors and after they severed innervation to the osphradium, a chemical sensory organ, suggesting that epi might act via a mechanism different from those previously known in snails. “Our present, as yet unproved, hypothesis is that epi directly works on neurons,” says Lukowiak. (The Journal of Experimental Biology)